Which is the safest zero cal sugar substitute which can be used with tea,coffeee or milk?

There are many brands in India.

Which generic is safe - Sucralose, Aspartame, Acesulfame K, Stevia Rebaudiana which is a herb ?

I read Aspartame and Acesulfame K are carcinogens .

Is sucralose safe ?

Stevia natural sweetener is good but its sweetness is very less .You have to put 3-4 pellets to make it sweet.